The present invention relates generally to gas turbine engine combustors, and more particularly, in one form, to a dry low emission combustion system that utilizes swirling and jet flows within the combustion chamber to provide stable aerodynamics.
Air pollution emissions are an undesirable by-product from the operation of a gas turbine engine that burns fossil fuels. The primary air polluting emissions produced by the burning of fossil fuels include carbon dioxide, water vapor, oxides of nitrogen, carbon monoxide, unburned hydrocarbons, oxides of sulfur and particulate. Of the above emissions, carbon dioxide and water vapor are generally not considered objectionable. However, air pollution has become a worldwide concern and many nations have enacted stricter laws regarding the discharge of pollutants into the environment.
Gas turbine engine designers have generally accepted that many of the by-products of the combustion of fossil fuel can be controlled design parameters, the cleanup of exhaust gases and regulating the quality of fuel. Oxides of Nitrogen (NOx) are one the pollutants that have been of particular concern to gas turbine engine designers. It is well known that in a gas turbine engine the oxidation of nitrogen is dependent upon the flame temperature within the combustion region. Many industrial gas turbine engines utilize premixing of the fuel with the compressor air to create a reactant mixture with lean stoichiometries to limit flame temperature and control NOx formation. Typically, a premixing section within the combustor prepares a combustible mixture upstream of the flame front, and therefore the combustor includes provisions to keep the flame from entering or igniting within the premixing section. Often the residence time and velocities within the premixing section are manipulated to discourage auto-ignition and flashback. As a result of this manipulation the residence time is many times limited, which results in incomplete mixing with increased NOx emission. Further, in many systems the burning temperatures are low enough that Carbon Monoxide (CO) emissions are increased.
A limitation associated with many prior dry low emission combustion systems is that they have tended to have combustion instability, which is manifested as noise. It appears that combustion instability results from a coupling of the combustion process with acoustical characteristics of the system. The associated resonances affect combustor performance and can quickly build to destructive levels. Many of the approaches to date for addressing the limitations of the prior dry low emission combustion systems have generally had limited success or caused a reduced system performance. The present invention satisfies the technological needs for combustion systems in a novel and unobvious way.
One form of the present invention contemplates a combustor for burning a fuel and gas mixture, comprising: a mechanical housing; a combustion chamber located within the mechanical housing and having a first end and a second end and an internal volume; a radial inflow swirler located at the first end and disposed in flow communication with the internal volume, the radial inflow swirler including a plurality of fuel dispensers for delivering the fuel into the gas within the swirler and a plurality of vanes for directing the fuel and gas flow into the internal volume to define a swirler flow; and, a first plurality of tubular premixers connected to the combustion chamber and in flow communication with the internal volume, each of the first plurality of tubular premixers deliver a premixed jet flow of the gas and fuel into the internal volume.
Another form of the present invention contemplates a combustor, comprising: a mechanical housing; a combustion chamber disposed within the mechanical housing and having a first end and a second end and an internal volume; a premixer coupled to the first end of the combustion chamber and in flow communication with the internal volume, the premixer including a swirler that delivers a swirling flow of fuel and gas to the internal volume through the first end; and, a dome positioned at the first end of the combustion chamber and extending into the internal volume, the dome having an outer surface contoured to minimize flow separation of the swirling flow of fuel and gas passing from the premixer and into the combustion chamber.
Another form of the present invention contemplates a combustor, comprising: a mechanical housing; a combustion chamber located within the mechanical housing and having a first end and a second end and an internal volume; a premixer coupled to the first end of the combustion chamber and in flow communication with the internal volume, the premixer including a swirler that delivers a swirling flow of fuel and gas to the internal volume through the first end; and, a dome located at the first end and within the internal volume of the combustion chamber, the dome extending along the circumference of the first end and having a convex cross-section.
Yet another form of the present invention contemplates a combustor, comprising: a cylindrical combustor chamber having a first end, a second end and an internal volume, the combustor chamber having a portion with a constant cross-sectional area, the combustor chamber having a plurality of first apertures in the portion and a plurality of second apertures in the portion, and the plurality of first apertures are axially spaced from the plurality of second apertures; a plurality of first tubular premixers are coupled to the combustor chamber, each of the plurality of first tubular premixers is in flow communication with one of the plurality of first apertures; and, a plurality of second tubular premixers coupled to the combustor chamber, each of the plurality of second tubular premixers is in flow communication with one of the plurality of second apertures.
In yet another form the present invention contemplates a combustor, comprising: a mechanical housing; a combustion chamber located within the mechanical housing and having an internal volume; and, a premixer coupled with the combustion chamber, the premixer comprising: a tubular member having a first end and a second end and a flow passageway therebetween; a fuel manifold disposed in fluid communication with the flow passageway for the delivery of a fuel into the flow passageway; and, twist mixer means for rotating the fluid flowing within the flow passageway, the twist mixer means positioned within the flow passageway.
In yet another form the present invention contemplates a combustor for burning a fuel and air mixture. The combustor, comprising: a combustor liner having a fist end, a second end and an internal volume; a premixer coupled to the first end of the combustor liner and disposed in flow communication with the internal volume, the premixer including a radial inflow swirler having a plurality of fueling passages for delivering the fuel into the air within the swirler and a plurality of vanes for directing the fuel and air flow from the premixer; a center body having at least a portion positioned within the premixer and located within a space defined between the plurality of vanes; a dome disposed between the first end of the combustor liner and the premixer, the dome having an outer surface contoured to minimize flow separation of the fuel and air flowing from the premixer into the internal volume; a plurality of first tubular premixers coupled to the combustor liner, each of the plurality of first tubular premixers in flow communication with the internal volume; and, a plurality of second tubular premixers coupled to the combustor liner, each of the plurality of second tubular premixers is in flow communication with the internal volume, and the plurality of second tubular premixers are spaced axially from the plurality of first tubular premixers.
One object of the present invention is to provide a unique combustion system.
Related objects and advantages of the present invention will be apparent from the following description.